His name was Sudan, and he was the last remaining male northern white rhino. He died in captivity at the Ol Pejeta Conservancy in Kenya this Tuesday.

His age was 45 years old, note that the average lifespan of White rhinoceros is 40 – 50 years.

The population of northern white rhinos has been decreasing since 1960 when about 2,000 rhinos were living on the grasslands of east and central Africa.

By 2008, researchers couldn’t find any. War, habitat loss, and poaching for their horns contributed to the subspecies’ extinction in the wild.

Rachel Nuwer is a science journalist and contributor on major media. Here’s what Rachel said about Sudan for The New York Times:

“Sudan is an extreme symbol of human disregard for nature,” said Jan Stejskal, director of international projects at the Dvur Kralove Zoo in the Czech Republic, where Sudan spent most of his life. “He survived extinction of his kind in the wild only thanks to living in a zoo.”

The White rhinoceros is (well, was) the third-heaviest land mammal in the world, while the first 2 are the Blue Whale first and African Bush Elephant second most heavy.

Northern white rhinos are a subspecies of southern white rhino, though some researchers argue they should be considered their own species. They’re hairier, smaller, and have different dental structures.

Scientists are trying to save the northern white rhino species, they’ll try to fertilize northern white rhino eggs in vitro and then implant embryos in surrogate southern white rhinos.

The process could take up to 15 years to accomplish. At which point, it may be too late to save the northern white rhino. Right now, there are two known rhinos of this subspecies left, both of which are female.